The present invention relates to a semiconductor memory device, and more precisely to a sense amplifier that improves a flip failure occurrence if a voltage applied across a bit line is within an acceptable threshold range when the data is delivered to the data bus and a driving method thereof.
The data stored or to be stored in a cell array is carried on the bit line of the semiconductor memory device. The data delivered between the bit line and the data bus is sensed and amplified by the sense amplifier.
Semiconductor memory devices are becoming smaller as they become more highly integrated. As a result, the layout area of the sense amplifier used in a semiconductor memory device tends to be reduced.
By reducing the layout area of the sense amplifier, the current driving capability of an NMOS transistor and a PMOS transistor that constitute the sense amplifier is reduced.
The voltage of a low data output terminal of the sense amplifier is boosted and the voltage of a high data output terminal of the sense amplifier is dropped by a precharge voltage on the data bus if the data amplified in both output terminals of the sense amplifier is delivered to the data bus by driving the column select signal, which is a signal selecting a column of the bit line.
At this time, a flip failure occurs where the data is inverted and amplified by a voltage offset from the threshold voltage of the PMOS transistor if the high data voltage and the low data voltage from the sense amplifier are within an acceptable threshold range.
That is, the flip failure of the bit line, such as in FIG. 1, can occur in the sense amplifier that has a smaller size
FIG. 1 is a drawing illustrating that a flipping error occurs so that the bit line /BL is amplified to a core voltage VCORE and the bit line BL is amplified to a ground voltage VSS if the voltage at both output terminals of the sense amplifier is within an acceptable threshold range when a column select signal YI is enabled, a pull-down driving signal SAN is enabled, and a pull-up driving signal SAP are enabled.